Sure thing! We've got 541 and we're gonna multiply it by 90. That's the same as adding 541 to itself 90 times.
Step 1: 0 + 541 = 541
Step 2: 541 + 541 = 1082
Step 3: 1082 + 541 = 1623
Step 4: 1623 + 541 = 2164
Step 5: 2164 + 541 = 2705
Step 6: 2705 + 541 = 3246
Step 7: 3246 + 541 = 3787
Step 8: 3787 + 541 = 4328
Step 9: 4328 + 541 = 4869
Step 10: 4869 + 541 = 5410
Step 11: 5410 + 541 = 5951
Step 12: 5951 + 541 = 6492
Step 13: 6492 + 541 = 7033
Step 14: 7033 + 541 = 7574
Step 15: 7574 + 541 = 8115
Step 16: 8115 + 541 = 8656
Step 17: 8656 + 541 = 9197
Step 18: 9197 + 541 = 9738
Step 19: 9738 + 541 = 10279
Step 20: 10279 + 541 = 10820
Step 21: 10820 + 541 = 11361
Step 22: 11361 + 541 = 11902
Step 23: 11902 + 541 = 12443
Step 24: 12443 + 541 = 12984
Step 25: 12984 + 541 = 13525
Step 26: 13525 + 541 = 14066
Step 27: 14066 + 541 = 14607
Step 28: 14607 + 541 = 15148
Step 29: 15148 + 541 = 15689
Step 30: 15689 + 541 = 16230
Step 31: 16230 + 541 = 16771
Step 32: 16771 + 541 = 17312
Step 33: 17312 + 541 = 17853
Step 34: 17853 + 541 = 18394
Step 35: 18394 + 541 = 18935
Step 36: 18935 + 541 = 19476
Step 37: 19476 + 541 = 20017
Step 38: 20017 + 541 = 20558
Step 39: 20558 + 541 = 21099
Step 40: 21099 + 541 = 21640
Step 41: 21640 + 541 = 22181
Step 42: 22181 + 541 = 22722
Step 43: 22722 + 541 = 23263
Step 44: 23263 + 541 = 23804
Step 45: 23804 + 541 = 24345
Step 46: 24345 + 541 = 24886
Step 47: 24886 + 541 = 25427
Step 48: 25427 + 541 = 25968
Step 49: 25968 + 541 = 26509
Step 50: 26509 + 541 = 27050
Step 51: 27050 + 541 = 27591
Step 52: 27591 + 541 = 28132
Step 53: 28132 + 541 = 28673
Step 54: 28673 + 541 = 29214
Step 55: 29214 + 541 = 29755
Step 56: 29755 + 541 = 30296
Step 57: 30296 + 541 = 30837
Step 58: 30837 + 541 = 31378
Step 59: 31378 + 541 = 31919
Step 60: 31919 + 541 = 32460
Step 61: 32460 + 541 = 33001
Step 62: 33001 + 541 = 33542
Step 63: 33542 + 541 = 34083
Step 64: 34083 + 541 = 34624
Step 65: 34624 + 541 = 35165
Step 66: 35165 + 541 = 35706
Step 67: 35706 + 541 = 36247
Step 68: 36247 + 541 = 36788
Step 69: 36788 + 541 = 37329
Step 70: 37329 + 541 = 37870
Step 71: 37870 + 541 = 38411
Step 72: 38411 + 541 = 38952
Step 73: 38952 + 541 = 39493
Step 74: 39493 + 541 = 40034
Step 75: 40034 + 541 = 40575
Step 76: 40575 + 541 = 41116
Step 77: 41116 + 541 = 41657
Step 78: 41657 + 541 = 42198
Step 79: 42198 + 541 = 42739
Step 80: 42739 + 541 = 43280
Step 81: 43280 + 541 = 43821
Step 82: 43821 + 541 = 44362
Step 83: 44362 + 541 = 44903
Step 84: 44903 + 541 = 45444
Step 85: 45444 + 541 = 45985
Step 86: 45985 + 541 = 46526
Step 87: 46526 + 541 = 47067
Step 88: 47067 + 541 = 47608
Step 89: 47608 + 541 = 48149
Step 90: 48149 + 541 = 48690

So, 541*90 = 48690